Keyboard printer with continuously rotating type member

ABSTRACT

A keyboard printer for use as a peripheral element of a computer in which the codes of the characters are pulses exhibiting with respect with a start pulse variable discrete phase shifts. This printer comprises means for continuously rotating first and a second wheels and a rotative arm carrying a mobile electrode. The first wheel has one magnetic tooth and the second wheel has a plurality of magnetic teeth, as many as characters on a rotative character wheel also driven by the same shaft as the two wheels and the arm. A pulse distributor comprises a common electrode and individual character electrodes. The keys are formed by two adjacent key electrodes which exhibit a small capacitance when not touched and a large capacitance when touched by the operator&#39;&#39;s finger tips. The common electrode is connected to the winding of an electromagnet cooperating with the second wheel. The individual character of electrodes are respectively connected to one electrode of the keys and the second electrodes of the keys are connected to the output of the printer.

United States Patent [72] Inventor [54] KEYBOARD PRINTER WITH CONTINUOUSLY ROTATING TYPE MEMBER 4 Claims, 9 Drawing Figs.

[52] US. Cl 197/18, 101/93, 197/49, 197/53, 197/98 [51] Int. Cl B4lj l/30 [50] Field of Search 197/18, 49, 53, 55, 98; 101/93 [56] References Cited UNITED STATES PATENTS 2,236,663 4/1941 Adams 197/53 2,782,308 2/1957 Rug 198/98 X 2,805,620 9/1957 Rosen et al. 101/93 3,142,247 7/1964 Sweeney 197/18 X 3,168,182 2/1965 Bernard et al. 197/18 X 3,227,258 1/1966 Pannier et a1.. 197/6.6 3,232,404 2/1966 Jones 101/93 X 3,289,805 12/1966 Kleinschmidt et al. 197/53 X 3,442,364 5/1969 Ragen 197/49 3,447,656 6/1969 Nyquist 197/55 X OTHER REFERENCES IBM TECHNICAL DISCLOSURE BULLETIN, Vol. 3, No.

11, Apr. 1961, article by W. A. Goddard entitled nonmechanical Keyboard page 31.

Primary Examiner-Edgar S. Burr Attorney-Abraham A. Saffitz ABSTRACT: A keyboard printer for use as a peripheral element of a computer in which the codes of the characters are pulses exhibiting with respect with a start pulse variable dis- .crete phase shifts. This printer comprises means for continuously rotating first and a second wheels and a rotative arm carrying a mobile electrode. The first wheel has one magnetic tooth and the second wheel has a plurality of magnetic teeth, as many as characters on a rotative character wheel also driven by the same shaft as the two wheels and the arm. A pulse distributor comprises a common electrode and inv dividual character electrodes. The keys are formed by two ad- PATENTEUJUNZSIQ?! 3,589,494

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KEYBOARD PRINTER WITH CONTINUOUSLY ROTATING TYPE MEMBER This invention relates to a keyboard printer as used as a terminal input and output element of a computer, and more particularly to a keyboard printer in which the keys do not need to be actuated but only to be grazed or lightly touched on.

The keyboard printer of the invention pertains to the known kind of printers in which the code of a given character is a pulse the phase shift or delay of which with respect to a start pulse represents the character.

The printer of the invention essentially comprises a character wheel, means for continuously rotating said character wheel and for selectively printing the characters without stopping of the wheel, means for distributing onto a plurality of character terminals, a start pulse and characters pulses, each character being defined by the delay between the start pulse and the character pulse, a plurality of touchoperated character keys, each including first and second electrodes, connections between the first of said electrodes and said character terminals, connections between the second of said electrodes and an output terminal, said key electrodes ex hibiting with each other a large capacitance when the operators finger tip is on the key and a small capacitance when it is v out of the key whereby a given character pulse is produced at said output terminal when the operator touches the corresponding key.

The invention will be more clearly understood from the following detailed description, reference being made to the accompanying drawings wherein;

FIG. l is a perspective view of a simplified form of a first embodiment ofa printer according to the invention;

FIG. 2 shows the patterns of the start and character pulses produced by the tone wheels;

FIGS. 3 and 4 relate to the wheel bearing the characters of the printer of FIG. 1;

FIGS. 5 and 6 relate to the signal distributor and to the printer keyboard according to the invention;

FIG. 7 is a perspective view of a simplified form of a second embodiment ofa printer according to the invention;

FIG. 8 represents the signal distributor of the printer of FIG. 7; and

FIG. 9 shows the electrical diagram of a signal distributor which does not need a compensation capacitor.

FIG. 1 is an exemplary nonlimitative view in perspective of a keyboard type printer for computer according to the invention. An electric motor 1 rotates continuously. The character wheel 10 has a cylindrical U-section forms a place to receive a typing" solenoid 11 secured to the printer frame by a support (not shown). A tone wheel has a single tooth 21 which is made of a magnetic material, so that once per revolution the tooth 21 produces a pulse like energization by induction of a winding 22 wound on a magnetic core 23. A tone wheel 30 is formed with a number of peripheral teeth made of a magnetic material so as to energize a winding 32 wound on a magnetic core 33 as many times per revolution as there are characters on'the character wheel. A capacitive distributor 40 has a rotating arm 41. A sheet 3 of printing paper is disposed on a laterally shifting roller or platen 2. A flexible printed circuit keyboard 50 is rigidly secured by a connecting strip 4 to the distributor 40.

A description will now be given of how the printer according to the invention operates, with reference to some characteristic features.

The character wheel 10 bears 50 characters or blanks. Corresponding to each actual character is a key, such as 51,, of the keyboard 50 which includes, in addition to character keys, the usual control keys, for instance, for controlling lateral movement of the carriage bearing the roller or platen 2.

The motor 1 rotates the mechanical system of the printer at a rated speed of 20 r.p.m., although the arhythmic nature of operation is such that there are very wide tolerances, for instance, of 20 percent, for this speed.

0 of the pulses delivered by the winding 32.

FIG. 2 shows the timing of these pulses.

Diagram (11) relates to the start pulses and diagram (b) to the character pulses. As these diagrams show, the offset between the two wheels 20 and 30 is such that the start pulse appears very briefly after the final character pulse of the immediately previous revolution.

The printout of a character is controlled by the computer by a real time program determining the delay or phase shift between the occurrence of a character pulse and the occurrence of the start pulse. This phase shift is 2rri/50 with i=1 to 50.

The program proceeds as follows:

a. Wait for a revolution pulse,

b. Count (nl character pulses,

c. Transmit the printout signal,

d. Provide sufficient delay, for instance, 0.05 sec., to cover the mechanical" times of the printer,

e. Leave the program.

Via a transistorized circuit (not shown in FIG. 1), the printout signal initiates the transmission of a heavy current pulse through the winding of the solenoid 11 which, for instance, has a plunger acting as a hammer to briefly press the required character on the paper 3 disposed on the platen 2. To print the characters on the paper the usual system of an inked ribbon can be used or, even better, special self-inking paper can be used, in which event the movement of the character during striking can be reduced considerably.

FIGS. 3 and 4 are views, in plan and section respectively, of the character wheel 10 (FIG. 1) and its typing or striking electromagnet or solenoid or the like 11. End 11 of the solenoid core strikes a character, as 121' (i having any of the values 1 to 50), and the character thus struck strikes the paper 3 on the platen 2 to print the character.

The characters can be made readily movable and light in weight if the wheel 10 in shape resembles a cylindrical tray made as a resilient metal stamping, the tray wall being cut along generatrices of the tray into tongues 12 .....12,-.....12 or equal widths. The type face characters are formed in relief at the free ends of the tongues by embossing. Advantageously, the tongues are bent towards the tray interior so that the typing position corresponds to the substantially vertical position of the tongues. A typing operation is of course immediately followed or preceded by an appropriate shift of the platen 2 to ensure correct character spacing along the line. A conven tional electromechanical facility (not shown in FIG. 1) is provided for this purpose. Of course, the reaction of the tongues 'or strips to bending causes vibrations, but partial damping thereof can be achieved by disposing at the bottom of the wheel 10 a plastics 14 which sticks satisfactorily to the metal of the wheel 10. Spacing can be provided by means of a blank tongue. The carriage return and line advance instructions can be carried out by electromechanical systems which do not concern the device according to the invention and which are controlled by a program whose channels in the computer are independent of the channels controlling the printout of a character combined with spacing and the spacing.

As will be shown hereinafter, operation of the printer according to the invention is such that transmission from the keyboard 50 (FIG. 1) combines the action of a finger of the hand on a key, as 51k, with reception by the computer of the two kinds of pulse delivered by the tone wheels 20, 30, through the agency of a real time program. The final result is that the computer records a definite code identifying each character keyed.

When a finger touches a key 51,. of the keyboard 50 relative to the character K, since the finger normally remains in con tact with the key for longer than 0.05 sec., more than one character pulse is transmitted to the computer. The character K must therefore be vaIidated"-i.e., only the first character pulse K must be considered and the following pulses K must be ignored until a pulse absence during one or more consecutive 0.05 sec. cycles has been detected.

The program of the computer for detecting a character therefore proceeds as follows:

a. Detect a first key pulse K;

b. Count the number of character pulses following the pulse K until a start pulse from the wheel 20 marks the complement (SO-k) ofthe character pulse number k;

c. Ignore the following key pulses K and wait, for instance,

two consecutive revolutions without pulses;

(1. Leave the program.

If the keyed character K is required to be printed, the program sequence just given must be followed by the printout sequence hereinbefore given controlling the printout of the character K.

The two program sequences hereinbefore given should overlap or be combined in the interest of speeding up printout. For instance, the printout instruction is transmitted before the completion ofstep (c) of the detecting sequence.

The mechanism for transmitting a key pulse will now be described in detail with reference to FIGS. and 6, where elements previously shown in FIG. I have the same reference numbers. Via the connecting strip 4 the keyboard 50 is ex tended to the cylindrical ring 40 forming part of the distributor. All this system is formed by a flexible plastics support, for instance, of mylar, having circuits printed on both its faces. The ring 40 is rigid because it is secured to the printer fraMe by a cylindrical insulating support which is outside the ring 40 and which is not shown in FIGS. 5 and 6. Near the top of its inside" surface the ring 40 bears an annular electrode 42 connected to end 32, of winding 32 of the core 33 allotted to wheel 30. As already stated, the same has on its periphery 50 teeth, one per printer character. The wheel 30 originates the character pulses" in the winding 32 (FIG. 2, diagram (b)). End 32 of winding 32 produces the same signals as those of FIG. 2 (b) but of opposite polarity, the winding 32 having a grounded center tap 32,.

Immediately below electrode 42 the ring 40 has 50 printed rectangular zones or individual electrodes 43,, 43 .....43,, 43,, 43 .....43 which have equal areas and are spaced evenly apart from one another. The keys of the keyboard 50, as 51,, 51,-, 51,, each take the form of two rectangular printed areas on the back" of the keyboard and are separated from one another by an unmetallized line. For instance, the key Sli is formed by the top area 521' and by the bottom area 53i. The top zones 52i, 52j, 52k of the keys, as 511', 51], 51k, are electrically connected to the zones 43i, 43j, 43k respectively by respective printed connections 41', 4], 4k. The bottom parts 531', 53], 53k of the same keys 511', 51j,51/ are interconnected by a common printed connection 54 which a compensating capacitor 34 connects to end 32 ofwinding 32.

Disposed on the front surface of the keyboard 50 opposite each key is an active electrode, as 55,-, which completely covers the two zones 521', 53i printed on the back and which is completely insulated. The front surface of the keyboard 50 is covered by grounded printed screening 56 extending around the electrodes, as 551. The rotating arm 41 which the motor 1 (FIG. I) rotates in the ring 40 is made of an insulating substance and has at its end a conductive part cylindrical plate 410 which constitutes a rotating electrode and is disposed opposite the annular electrode 42 and the zones 43,...431, 43j, 43k....43 The character electrode separation between two zones 431, 43] can always be very reduced, but the width of the plate 410 is always less than the distance between the shared edges of two contiguous zones. The surface of the blade 410 cannot therefore cover two adjacent zones simultaneously, thus ensuring that the character pulse is distributed satisfactorily to the individual electrodes.

Operation of the distributor 40 associated with the keyboard 50 is as follows:

During each revolution of the arm 41 the 50 character pulses are distributed one each to the 50 keys of the keyboard 50 via the capacitor provided by the plate 410 the annular electrode and the individual electrodes. For each key, as 511, pulse delivered at end 32, of winding 32 has a small amplitude at the collecting electrode 54 because of the presence of the electrodes 521', 531' which are disposed opposite the electrode 551'. Also, the same pulse sampled at end 32, of winding 32 has the opposite polarity; its presence on the collecting electrode 54 means that the potential thereof is substantially zero.

If a finger tip is now placed on electrode 55i with sufficient pressure to give a suitable contact area, a capacitance is introduced between the electrode 551' and ground as embodied by screening 56 of keyboard 50. Consequently, the pulse from terminal 32, is appreciably attenuated whereas the signal pulse from terminal 32 is not attenuated. After amplification and clipping by a circuit 60, the signal from terminal 32 is routed towards the appropriate input of the computer as a key pulse.

FIG. 7 represents a second embodiment of the keyboard printer for computer according to the invention. The parts of the printer which are unchanged with respect to the embodiment of FIG. 1 are given the same reference numerals. The parts which are modified are the character wheel, the pulse distributor and the compensation capacitor. Further the driving shaft of the printer is now disposed horizontally.

The character wheel has the shape of a disc with outer radial tongues 101, 102,... made ofa resilient metal. The type face characters are formed in relief at the free ends of the tongues by embossing. The character wheel 100 cooperates with a striking electromagnet 11. Due to horizontality of the shaft carrying the character wheel, the wheel can be disposed so that the upper character of the wheel be in the horizontal diametrical plane of platen 2. Thus, the character wheel is not a mask for the operator and does not prevent him from reading the characters just printed. Distributor 400 has a plane structure instead of a cylindrical structure. The sheet of plastics carrying distributor 400 and keyboard 50 is folded at right angle in such a way that the distributor is vertical and the keyboard horizontal.

In FIG. 8, the distributor has been unfolded so as to lie in the horizontal plane. It comprises three metallized coaxial rings 420, 441, 442 forming three common electrodes, a plurality of metallized radial individual electrodes 430i, 430j, 430k,....and a diametrical arm 41 in dielectric material carrying outer conductive plates 410 and 443. Plate 443 forms with rings 441 and 442 a three electrode capacitor which plays the part of the compensation capacitor 34 of FIG. 5. Plate 410 forms with ring 420 and individual electrodes 430, (i=l to 50) a distributor capacitor.

Annular electrode 441 is connected to the common terminal 54 of the capacitive keys and annular electrode 442 is connected to terminal 32 of winding 32 in the same manner as the two electrodes of compensation capacitor 34 was connected to 54 and 32 FIG. 9 represents a distributor-keyboard arrangement wherein a compensation signal like that produced at terminal 32, is no longer needed.

Distributor 400 of FIG. 9 is similar to distributor 400 of FIG. 8 except that ring electrodes 441 and 442 are omitted. Rotative arm 41 only carries plate 410, plate 443 being omitted.

The connection between distributor electrodes as 4301' and keys as 5101' comprise the primary winding of transformers as 701'.

The keys are no longer constituted by two metal regions separated by an insulating gap but by single metallized regions as 510i surrounded by a conductive screen 511 playing the part of screen 56 of FIG. 6. Screen 511 is grounded, The key regions 510 are coated with a thin insulating sheet such as a mylar sheet which the operators finger tip can touch on.

Annular electrode 420 is connected to an oscillator having for instance a frequency between O.l and I Mhz.

When the operator touches a key, as 510i, the capacitance between the key 5101' and the grounded screen 511 increases and the loss resistance of the mylar sheet decreases due to the finger pressure. A high frequency current flows in the primary winding of the transformer. The secondary windings are serially connected to the input of the computer. Preferably, the set of secondary windings is tuned on the oscillator frequency by capacitor 80 to reinforce the output signal level. Annular ring 420 is still connected to winding 32 for synchronizing the printer and the computer. The output signals are pulses of a high frequency carrier.

A number of variants are possible. For instance, special printer instructions, such as carriage return or line spacing, can be carried out by means other than auxiliary connections from the computer and can be performed by the normal printout route if each operation is given an imaginary printed character. The strip is devoid of character but is elongated in height over a predetermined portion of its width so as to pressure-operate a particular local contact controlling the required operation. 7

What I claim is:

1. A keyboard printer for use as a peripheral element of a computer comprising a character wheel, means for continuously rotating said character wheel and for selectively printing the characters without stopping of the wheel, means for distributing onto a plurality of start and character terminals a start pulse and character pulses, each character being defined by the delay between the start pulse and the character pulse, a plurality of touch-operated character keys each including first and second electrodes, connections between the first of said electrodes and said character terminals, an annular electrode a rotating electrode sequentially and capacitatively coupling said annular electrode to each one of a plurality of character electrodes each constituting one of said character terminals, connections between the second of said electrodes and an output terminal, said key electrodes exhibiting with each other a large capacitance when the operators finger tip is on the key and a small capacitance when it is out of the key, whereby a character pulse is produced at said output terminal when the operator touches the corresponding key.

2. A keyboard printer as set forth in claim 1 in which the start and character pulse distributing means comprise a first rotative wheel with one magnetic tooth and a first electromagnet cooperating therewith, a second rotative wheel with a plurality of equally spaced magnetic teeth and a second electromagnet cooperating therewith and having a winding with a grounded center tap, a dielectric cylinder coaxial with said first and second rotative wheel, an annular common electrode disposed around said cylinder and a plurality of character electrodes radially and equiangularly spaced on said cylinder and connected to the character keys, and electrode-carrying rotative arm forming with said annular common electrode and said character electrodes a capacitor means for connecting said annular common electrode to the first terminal of the winding of the second electromagnet, a compensation capacitor, means for connecting in parallel the second key electrodes to a terminal of said compensation capacitor and means for connecting the other terminal of said compensation capacitor to the second terminal of said second electromagnet.

3. A keyboard printer as set forth in claim 1, in which the start and character pulses distributing means comprise a first rotative wheel with one magnetic tooth and a first electromagnet cooperating therewith, a second rotative wheel with a plurality of equally spaced magnetic teeth and a second electromagnet cooperating therewith and having a winding with a grounded center tap, a dielectric plane sheet parallel to said first and second rotative wheels, three annular coaxial electrode rings disposed on said plane sheet and a plurality of character electrodes radially and equiangularly spaced apart on said plane sheet and connected to the character keys, a rotative arm carrying two mobile electrodes, the first mobile electrode forming with the first annular electrode ring and said character electrodes a first capacitor and the second mobile electrode forming with the second and third annular electrode rings a second compensation capacitor, means for connecting said first annular electrode ring to the first terminal of the winding of the second electromagnet, means for connecting said second annular electrode ring to the second terminal of the winding of the second electromagnet and means for connecting in parallel the second key electrode to the third annular electrode ring.

4. A keyboard printer as set forth in claim 1 in which the start and character pulse distributing means comprises a first rotative wheel with one magnetic tooth and a first electromagnet cooperating therewith, a second rotative wheel with a plurality of equally spaced magnetic teeth and a second electromagnet cooperating therewith, a dielectric plane sheet parallel to said first and second rotative wheels, an annular electrode ring disposed on said plane sheet and a plurality of character electrodes radially disposed and equiangularly spaced on said plane sheet, a rotative arm carrying a mobile electrode and forming with the annular electrode ring and the character electrodes a capacitor, an oscillator with two output terminals, a plurality of transformers having primary and secondary windings, means for connecting the character electrodes respectively to the first key electrodes through the primary windings of said transformers, means for connecting one output terminal of the oscillator to said annular electrode ring, means for connecting in parallel the second key electrodes to the second output terminal of the oscillator and means for connecting the windings of the first and second electromagnets on the one hand and the secondary windings of the transformers in series on the other hand to the output terminal of the printer. 

1. A keyboard printer for use as a peripheral element of a computer comprising a character wheel, means for continuously rotating said character wheel and for selectively printing the characters without stopping of the wheel, means for distributing onto a plurality of start and character terminals a start pulse and character pulses, each character being defined by the delay between the start pulse and the character pulse, a plurality of touch-operated character keys each including first and second electrodes, connections between the first of said electrodes and said character terminals, an annular electrode a rotating electrode sequentially and capacitatively coupling said annular electrode to each one of a plurality of character electrodes each constituting one of said character terminals, connections between the second of said electrodes and an output terminal, said key electrodes exhibiting with each other a large capacitance when the operator''s finger tip is on the key and a small capacitance when it is out of the key, whereby a character pulse is produced at said output terminal when the operator touches the corresponding key.
 2. A keyboard printer as set forth in claim 1 in which the start and character pulse distributing means comprise a first rotative wheel with one magnetic tooth and a first electromagnet cooperating therewith, a second rotative wheel with a plurality of equally spaced magnetic teeth and a second electromagnet cooperating therewith and having a winding with a grounded center tap, a dielectric cylinder coaxial with said first and second rotative wheel, an annular common electrode disposed around said cylinder and a plurality of character electrodes radially and equiangularly spaced on said cylinder and connected to the character keys, and electrode-carrying rotative arm forming with said annular common electrode and said character electrodes a capacitor means for connecting said annular common electrode to the first terminal of the winding of the second electromagnet, a compensation capacitor, means for connecting in parallel the second key electrodes to a terminal of said compensation capacitor and means for connecting the other terminal of said compensation capacitor to the second terminal of said second electromagnet.
 3. A keyboard printer as set forth in claim 1, in which the start and character pulses distributing means comprise a first rotative wheel with one magnetic tooth and a first electromagnet cooperating therewith, a second rotative wheel with a plurality of equally spaced magnetic teeth and a second electromagnet cooperating therewith and having a winding with a grounded center tap, a dielectric plane sheet parallel to said first and second rotative wheels, three annular coaxial electrode rings disposed on said plane sheet and a plurality of character electrodes radially and equiangularly spaced apart on said plane sheet and connected to the character keys, a rotative arm carrying two mobile electrodes, the first mobile electrode forming with the first annular electrode ring and said character electrodes a first capacitor and the second mobile electrode forming with the second and third annular electrode rings a second compensation capacitor, means for connecting said first annular electrode ring to the first terminal of the winding of the second electromagnet, means for connecting said second annular electrode ring to the second terminal of the winding of the second electromagnet and means for connecting in parallel the second key electrode to the third annular elecTrode ring.
 4. A keyboard printer as set forth in claim 1 in which the start and character pulse distributing means comprises a first rotative wheel with one magnetic tooth and a first electromagnet cooperating therewith, a second rotative wheel with a plurality of equally spaced magnetic teeth and a second electromagnet cooperating therewith, a dielectric plane sheet parallel to said first and second rotative wheels, an annular electrode ring disposed on said plane sheet and a plurality of character electrodes radially disposed and equiangularly spaced on said plane sheet, a rotative arm carrying a mobile electrode and forming with the annular electrode ring and the character electrodes a capacitor, an oscillator with two output terminals, a plurality of transformers having primary and secondary windings, means for connecting the character electrodes respectively to the first key electrodes through the primary windings of said transformers, means for connecting one output terminal of the oscillator to said annular electrode ring, means for connecting in parallel the second key electrodes to the second output terminal of the oscillator and means for connecting the windings of the first and second electromagnets on the one hand and the secondary windings of the transformers in series on the other hand to the output terminal of the printer. 